A Simulation Study on the Shimmy of Heavy Vehicles with Dependent Suspension

This paper presents the numerical simulation of front wheel shimmy for a CA10 tank truck. A mathematical model with five degree of freedom, referring to the influence of the structure above suspension on shimmy, is established. The simulation results show that there exist a sensitive interval where those parameters, including tie-rod stiffness, steering gear stiffness, steering gear damping, equivalent damping of wheel around kingpin, tire cornering stiffness, tire drag and kingpin caster angle, etc, have great influences on forced shimmy. At a certain speed, the above parameters may make the system form negative damping and lead to self-excited shimmy. The coupling shimmy occurs when the system proper structure parameters and speed make the system form negative damping and there is unbalance on the front wheels. The unbalance on the front wheels has small influence on the coupling shimmy and self-excited shimmy is great at low speeds. However, it increases the amplitudes of coupling shimmy remarkably and forced shimmy is great at high speeds.